High and low pressure turbine components including rotor blades, vanes, and stators are generally made of nickel based alloys to stand hostile environments including high temperature. Electroformed Ni has been used in non-high temperature applications. Nickel has excellent high temperature creep resistance, but poor oxidation resistance. Thus, the addition of chromic or alumina formers to increase the oxidation resistance of the nickel based alloys is desirable, particularly for high temperature environment such gas turbine engines.
Electroforming is a metal forming process that builds up metal components through electrodeposition. The part or component is produced by depositing a metal skin onto a base form, known as a mandrel which is removed after the electrodeposition is done. Electroforming differs from electroplating in that the deposit (e.g., Ni—Cr alloy) is much thicker and can exist as a self-supporting structure when the mandrel is removed.
Electroformed Ni—Cr alloys can provide a cost-effective technique to fabricate high temperature-resistant structures with complex geometries, tighter tolerance, and oxidation resistance. Typically, electrodeposition in the conventional plating chemistry has not been successful in forming Ni—Cr alloys with high chromium content (>8% wt., 20% wt. preferred) that is substantially thicker than 10 μm.
Accordingly, it is desirable is to electroform Ni—Cr alloys thicker than at least 10 μm to make high temperature and oxidation-resistant turbine engine parts having complex geometries and requiring tighter tolerance. Further desirable considerations include the cost effectiveness and environmental impact of the deposition process.